In recent years, many people have kept animals such as dogs and cats indoors, and bathing of such pet animals has been performed routinely. Thus, various shampoos suitable for use on hair coats of pet animals have been developed. For example, there are some shampoos comparable or superior to those for human in terms of good sense of use, such as foaming properties, shininess, and smoothness.
In contrast, in the case of dogs, cats and the like, dermatoses are often caused by bacteria, fungi and the like adhered to their hair coats. Additionally, ears of such animals are easily subject to invasion by fungi due to the structure, and are also liable to develop otitis externa. Therefore, shampoos for animals are typically required to have effects comparable or superior to those for human also in an antimicrobial activity (against bacteria and fungi).
Also in patients with human atopic dermatitis, infectious disease complications due to growth of bacteria on skin have become a problem.
As a common means to impart an antimicrobial activity to a detergent composition such as shampoos, irrespective of subjects on which the compositions are used, it is contemplated to use antimicrobial ingredients (preservatives or microcidal agents) blended in cosmetics to prevent deterioration of the products, such as benzoic acid, sodium benzoate, para-hydroxybenzoic acid esters (parabens), sorbic acid, dehydroacetic acid, phenoxyethanol, benzalkonium chloride, benzethonium chloride, and chlorohexidine.
However, since each of these ingredients has problems such as strong irritation to the skin and eyes and allergies, the amount that can be blended is limited. Thus, it was difficult to provide the subjects with a sufficient antimicrobial activity by use of shampoos.
For such problems, as a microcidal agent that can be blended to pharmaceuticals, cosmetics, and foods and that provides a potent effect in a small amount, an antiseptic microcidal agent containing, for example, 1,2-alkanediol and an imidazoline-based amphoteric surfactant is suggested (Patent Document 1).    Patent Document 1: Japanese Patent No. 4086794